Various kinds of adjusting mechanisms of the above-mentioned type are already known. Thus, Swiss Patent No. 500,729 describes a device in which at least one jaw of one part of two relatively adjustable parts is guided in a smooth bore in the other part and has a thread, with which a threaded nut cooperates. Said nut is held in a recess of the second part, and the adjustment of the two parts occurs through a relative rotation between a pin and threaded nut. For adjusting the heel gripping member to various boot sizes, cross bores are herein provided in the release plate into which the pin-shaped, threaded leg of the rectangularly bent adjusting bolt of the heel gripping member can be inserted from both sides. For the fine adjustment or adjusting to the boot, a threaded sleeve engages the threaded leg, which threaded sleeve forms the continuation for the heel gripping member.
Similar devices are described in Austrian Patent No. 291,830 and French Patent No. 2,117,324. A similiar construction which permits a rough adjustment has been shown in Austrian Patent No. 306,598. Here, however, a fine threaded adjustment is not obtained.
Even though all devices permit the adjustment to various boot sizes, the adjustment itself is somewhat complicated and, due to the danger of dirt getting into the cross bores, considerable cleaning operations are necessary. If, however, these cross bores are provided with covers -- which is easily possible -- then this results in additional expense.
The object of the invention is to produce an adjusting mechanism of the type described above, where the entire adjusting mechanism is stored in a closed part, namely in the sole plate. This overcomes the above-described disadvantages of the previous adjusting mechanisms and assures in addition a simple adjustment. Further, the invention permits also a finer adjustment in a single operation.